Primary bilateral Burkitt lymphoma of the lactating breast: a case report and review of the literature.

Burkitt lymphoma (BL) is a highly aggressive neoplasm, which frequently affects the ileocecal region in the sporadic form and the jaw in the endemic form; however, the breast is a rare primary site of this tumor. Here we describe a case of primary bilateral breast BL presenting during lactation in a 23-year-old woman. Excisional biopsy of breast masses demonstrated a B-cell lymphoma with a characteristic 'starry sky' pattern highly suggestive of BL. The neoplastic cells strongly expressed CD20 and CD10, and showed proliferative activity as measured by Ki-67. An IGH-MYC gene fusion indicating the presence of a typical Burkitt translocation t(8;14)(q24;q32) in the tumor tissue was detected by fluorescent in situ hybridization. The present case, along with a comprehensive review of the literature, demonstrates that BL of the breast should be considered in the differential diagnosis of lesions of the breast during lactation. Whether hormonal or antigenic factors trigger Burkitt lymphomagenesis in the lactating breast warrants further investigation.